Meta's tag base is very different than the rest of the trilogy - we expect and understand pretty much all tags to refer to components of the Stack Overflow system. For example, if a question is tagged [replies] I would expect that it refers to either comment replies or matters of the envelope, and if it is tagged [required-tags] I would expect that it refers to the 4 tags that are required on Meta.
As far as I've seen, Meta tries to avoid using tags that mean explicitly identical concepts to the sister sites. For example, we have a [css] tag that refers to matters of CSS pertaining to the sites, it is not used for general CSS like on the other sites. In a more recent and applicable example, we can look at this question, which is not closed but is also not a question that belongs on Meta. The current [advanced-search] tag on Meta is inappropriate (it would normally refer to SO's in-house advanced search, but we can't simply change it to [search] because the [search] tag on Meta refers to searching through Stack Overflow as opposed to general searching.
I can conclude that these questions should not be tagged in the same way they'd be tagged on the appropriate site, because the tags would be inappropriate in the context of Meta. But they likewise cannot simply be tagged something like [belongs-on-stackoverflow], otherwise the whole battle to destroy those tags on the other sites would have been for naught.
There is a mirror to this issue in the sister sites, which is what to do about tags on questions that are migrated to Meta. The tags used for Meta questions are poisonous to the other sites, they propagate in number and promote the usage of tags inappropriately to those who do not yet know any better. Last I inquired about this, the solution given to me was to just flag the question for a moderator to delete the stub.
Is this what should be done for off-topic questions on Meta? Should they just be primed for deletion, since they do not have any use to remain on Meta? Or have we an alternative tagging solution that can be used to prevent these off-topic questions from polluting the contents of existing tags? Maybe clear them of all tags, if it is possible for a moderator to do such?